Like mayo, I'm also a physician (am open to an ortho correcting me). To my knowledge, you're overestimating the sensitivity of these tests. For instance, Lachman can miss 20% of ACL tears, and it's likely somewhat higher in the hyperacute setting, particularly in a highly muscled world class athlete. So although you agreed the extent and magnitude of an injury is determined by MR, the type is as well. It's possible the MR reveals ACL, MCL, and meniscal injuries that physical exam either misses or is equivocal for.
The other variable is that for operator dependent tests like these, these types of studies are often performed in ideal settings with experienced, highly competent, highly trained clinicians, so in the "real world," I'm not sure the sensitivity is even that high for Lachman. Even though it's a rich sport and rich team, you just don't know. In my specialty, I know of good-but-not-great practices covering major sports teams.
"There is simply no reliable way of predicting the type, extent and magnitude of injury without an MRI" is a true statement, (well I suppose you can argue over what "reliable" means). And MRI itself is often operator and machine dependent, although less so for MSK.